Corrosion Studies of Weldment on AA5083 in GTAW Process

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CORROSION STUDIES OF WELDMENT ON AA5083 IN GTAW PROCESS Navaneethakrishnan.N#1,Goudilyan.M#2, Balakrishnan.A#3 #1,2Assistant

Professor ,Department of Mechanical Department Scholar, Department of Mechanical Department Sri Shanmugha College of Engineering & Technology, Salem, Tamil Nadu #3UG

---------------------------------------------------------------------***--------------------------------------------------------------------metal. There are various welding processes used in industry Abstract— Occur in spite of the fact that the proper base metal and filler metal have been selected, industry codes and

today, the main factors for their distinctions being the Source

standards have been followed, and welds have been deposited

of the energy used for welding, and the means of protection

that possess full weld penetration and have proper shape and

or cleaning of the welded material.

contour. It is not unusual to find that, although the wrought

The corrosion is one of major problem in all the

form of a metal or alloy is resistant to corrosion in a particular environment, the welded counterpart is not. Further welds can

kinds of materials. Especially in industries they are only most

be made with the addition of filler metal or can be made

suffering people. Because of corrosion the material

autogenously (without filler metal). However, there are also

properties and behaviours will get changed and also

many instances in which the weld exhibits corrosion resistance

breakage of the material takes place.

superior to that of the non-welded base metal. There also are

Aluminum alloy AA5083 important lightweight

times when the weld behaves in an erratic manner, displaying

structural materials that have been widely used in Aviation,

both resistance and susceptibility to corrosive attack. In this

aerospace, transportation and other areas for their excellent

work we are going to identify the corrosion rate of AA5083

specific strength and good Weldability. In recent years, the

weldment and the base metal during Gas Tungsten Arc welding

applications of aluminum alloy sheets and their welded

process in different currents and voltage conditions by using weight loss method. Since the AA5083 has a wide range of

structures have drawn more and more attention because of

application in ship building prcess. And also this test on

their light weight and ease of processing.

AA5083 will help to understand the variations of corrosion

In this work to analyses the corrosion behaviours of

rate of specimens in different process parameters during

Aluminium Alloy. So we are select the base material as

welding and also it help to select the parameter which will

Aluminium Alloy 5083. By Gas Tungsten arc welding process

reduce the corrosion rate of weldment.

we will make butt welding on the base material. When the

Keywords— Corrosion, Weight loss method, Corrosion rate, welding,AA5083

welding work we going to change the process parameters

Introduction

of base metal with different process parameters in Gas

like current and voltage values. So we will take few quantity

Welding is defined by the American Welding Society (AWS)

Tungsten arc welding.

as a localized coalescence of metals or non-metals produced

After welding process we cut done the welded

by either heating of the materials to a suitable temperature

portions of material. Then polishing process carried out on

with or without the application of pressure, or by the

welded and non-welded materials. The polished work piece

application of pressure alone, with or without the use of filler

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III.CORROSION IN WELDMENTS

of microstructures will take for competition. After that the cutter portion will tested by weight loss method .now the corroded portion of microstructure will take for comparison.

Corrosion failures of welds occur in spite of the fact

By this process all the corrosion rates of different process

that the proper base metal and filler metal have been

parameter welded specimens are compared.

selected, industry codes and standards have been followed,

This comparison will give the result of which kind of process

and welds have been deposited that possess full weld

parameters will give less corrosion rate in future on AA5083.

penetration and have proper shape and contour. It is not unusual to find that, although the wrought form of a metal or

II.MATERIAL PROPERTIES

alloy is resistant to corrosion in a particular environment,

Aluminium is remarkable for its low density and

the welded counterpart is not. Further welds can be made

ability to resist corrosion due to the phenomenon of

with the addition of filler metal or can be made autogenously

passivation. Structural components made from aluminum

(without filler metal). However, there are also many

and its alloys are vital to the aerospace industry and are

instances in which the weld exhibits corrosion resistance

important in other areas of transportation and structural

superior to that of the unwedded base metal. There also are

materials. The most useful compounds of aluminium, at least

times when the weld behaves in an erratic manner,

on a weight basis, are the oxides and sulphates. Aluminium

displaying both resistance and susceptibility to corrosive

5083 is a high strength non-heat treatable alloy in

attack. It is sometimes difficult to determine why welds

commercial use. The major additive in the alloy is

corrode; however, one or more of the following factors often

Magnesium. It has good formability and weldability and

are implicated:

retains excellent tensile strength in the weld zone. It has

•

Weldment design

excellent resistance to corrosion and high strength-to-weight

•

Fabrication technique

•

Welding sequence

•

Moisture contamination

•

Oxide film and scale

•

Weld slag and spatter

ratio. The experimental material is selected as 5083 Al alloy sheets of 10 mm thickness, which is welded by GTA Welding.

Table 1: Properties of AA5083 S.No

Parameters

Symbol

Values

Units

1

Young’s Modulus

E

72

GPa

2

Poisson's Ratio

ʋ

0.33

-

3

Density

Ρ

2650

Kg/m3

4

Tensile Strength

σt

260

MPa

5

C

900

J/kg K

6

Specific Thermal Capacity Thermal Conductivity

K

121

W/Mk

7

Thermal Expansion

Α

25X10-6

/K

8

Melting Point

-

570

0C

9

Latent Heat

0.80x10-9

J/m3

10

Liquids Temperature

638

0C

591

0C

11

Solids Temperature

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3.1

CORROSION TESTING

AND

MONITORING

TECHNIQUES

|

1.

Weight loss coupon

2.

Oxalic test

3.

Ferritic test

4.

Electrical resistance (ER)

5.

Electrochemical impedance spectroscopy (EIS)

6.

Potentiodynamic anodic polarisation

7.

Electrochemical noise

8.

Hydrogen monitoring

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3.1.1 WEIGHT LOSS ANALYSIS The simplest, and longest-established, method of estimating corrosion losses in plant and equipment is weight loss analysis. A weighed sample (coupon) of the metal or

The coupons were weighed after cleaning to determine the

alloy under consideration is introduced into the process, and

general corrosion rates in each solution. In all cases where

later removed after a reasonable time interval.

the coupons were immersed in solutions that contained 3 M

 

Simple - No sophisticated instrumentation is

nitric acid, the general corrosion was so severe that the

required to obtain a result.

stamped identification marks were no longer visible. In these

Direct - A direct measurement is obtained, with no

cases, the total weight and total surface area of the 2 coupons

theoretical assumptions or approximations.

were added together to obtain an average corrosion rate for the material in a given solution.

Weight Loss and Corrosion Rate Determination In the laboratory, outer soil debris on the coupons

The corrosion rates for each test are shown in Table.

was carefully removed. They were then cleaned with

The corrosion rates appear to be reproducible as coupons

inhibited acid (15% HCl) to remove corrosion products on

from the same solution had similar corrosion rates. The

the surface of the coupons according to ASTM G1 (Standard

corrosion rates for both types of steel were also similar for

Practice for Preparing, Cleaning, and Evaluating Corrosion

the same test solution.

Test Specimens). The coupons were then rinsed under

3.1.2 OXALIC ACID CORROSION TEST

running water. Next, the coupons were placed in an oven at 70°C for 15 minutes to dry them. After drying, they were

The oxalic acid etch test is a rapid method of

placed in a desiccator to cool after which they were weighed

screening specimens of certain stainless steel grades which

to a constant weight using a Mettle Toledo weighing balance

are essentially free of susceptibility to intergranular attack

(New Classic ML 204, Switzerland). The weight of the

associated with chromium carbide participates. The test is

retrieved coupons before cleaning was compared to the

used for acceptance, but not rejection, of material.

initial weight, the difference indicating the metal loss during

This test may be used in conjunction with other tests

the exposure period. The corresponding average percentage

to provide a quick method for identifying specimens that are

weight loss (APWL) and corrosion rate (CR) were calculated.

certain to be free of susceptibility to rapid intergranular

Corrosion rate was calculated assuming uniform corrosion

attack. These specimens are identified by means of their etch

over the entire surface of the coupons. The corrosion rate in

structures.

mils per year (mpy) was calculated from the weight loss

IV. EXPERIMENTAL WORK

using the formula: The weight loss is converted to a

Specimen Preparation

corrosion rate (CR) or metal loss (ML), as follows:

Specimen Preparation Sectioning & Cutting Course Grinding

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Manual Preparation Specimen polishing by Sic abrasive paper Rough polishing Final Polishing Fig 3. Corrosion test samples in solution

Testing procedure



Take the test samples from the solution after 3 hours.



Polish the AA5083 material test samples by using silicon carbide sheet



By polishing machine polish the test samples with abrasive mixture. Here abrasive mixture is prepared

by Al2O3 (aluminum oxide) mixed with distilled

Fig 4. Specimen 1: After corrosion

water.

Fig 1 .

Fig 5. Specimen 2: After corrosion

Specimen 1: before corrosion test



Measure the weight (W2) of all the 5 tested samples by weighing machine after corrosion test.



Find the corrosion rate by using following formula.

Rcorr = 104 x

Fig .2. Specimen 2: before corrosion test



Prepare the 3 normality HCL solution with distilled water. For 100ml of solution add 27ml of HCL with

V. RESULT AND DISCUSSION

73ml of distilled water in 5 different beakers for 5

Weight loss method Calculations:

sample specimens. 

1 Normality of HCL solution

Take weight (W1) of all the 5 samples by weighing

In 100 ml of solution with 1 normality requires 81ml of

machine in grams before corrosion test. 

distilled water and 9ml of concentrated HCL acid.

Take the dimensions of all the AA5083 samples

For 3 normality HCL solution,

before corrosion test piece. 

= 9 ml.

Distilled water

Dip the samples in different beakers up to 48 hours.

= 73 ml

Concentrated HCL = 27 ml Sample 1: Density of the material (ρ)

= 7.8 grams/cm3.

Time (t) = 48 hours.

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Dimensions of the material:

Table 2: Corrosion rates with process parameters

Dimensions 1 :( for two sides)

Sa

Length =5cm Breath =1.3cm Dimensions 2 :( for two sides) Length =5cm

Area 1 = length x breath x 2 (for two sides) =5 x 1.3 x 2

Corrosio

Volt

before

after

weight

n

le

rent

age

corrosi

corrosi

loss

Rate

No.

I

V

on

on

W

Rcorr

(am

(vol

W1

W2

(W1-W2)

(1x103µ

ps)

ts)

(grams

(grams

(grams)

m/year)

)

)

11 12.2 13.6 14.7 15.9

9 9.2 9.6 10 10

2 3 4 4.7 5.9

53.8 80.7 107.6 126.4 158.7

1 2 3 4 5

Area calculation:

Total

Cur

Dimensions 3 :( for two sides) Breath =1cm

Weight

mp

Breath =1cm Length =1.3cm

Weight

200 210 220 240 265

23 23 22 24 24

Area 1 =13cm2.

VI. CONCLUSION

Area 2 = length x breath x 2 (for two sides)

By this project we analyzed the corrosion behaviors of Gas

=5 x 1 x 2

tungsten arc welded AA5083. We were took 5 different specimens,

Area2 =10cm2.

all are differ by process parameters like current and voltage when

Area 3 = length x breath x 2 (for two sides)

Gas tungsten arc welding process.

=1.3 x 1 x 2

Through this results by the comparison of all different

Area 3 =2.6cm2.

specimens we suggest that we can maintain process parameters as

Total Area =Area1+Area2+Area3

follows means we can reduce the corrosion rate of weldment in

=13+10+2.6

AA5083 with Gas tungsten arc welding process.

Total Area =25.6cm2

Current =200 amps

Weight loss calculation

Voltage =23 volts

Weight of the material before corrosion (w1)

By this parameters we can achieve the less quantity of

= 15.9 grams.

corrosion rate. As

Weight of the material after corrosion (w2)

Corrosion rate =53.8 x 103 µm/year

= 10 grams

Through our project we identified that when the current

Weight loss (W) = W1-W2

value of welding process increase the corrosion rate of the

= 15.9-10

weldment will be decreased.

W = 5.9 grams.

Our future work will be how to prevent the

Corrosion rate formula:

corrosion in weldment of AA5083 .so we will going to give

Rcorr = 104 x

the coatings by different Nano particles.

Rcorr = 104 x

REFERENCES

=158.7x103 µm/year.

Rcorr =0.1587 meter/year.

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[1] Adeosun, S.O., Sanni, O.S., Agunsoye, J.O., Lawal, J.T. and

Technology, Sankari. His area of interest includes

Ayoola, W.A., “Corrosion Responses of Welded Mild Steel

Friction Surfacing, Energy conservation and

Embedded in Coastal Soil Environment”, International

utilization and Welding Technology.

Conference

M.GOUDILYAN completed his Bachelor

[2] Beech, I.B. and Coutinho, C.L.M., “Biofilms on corroding

Degree in Mechanical Engineering from

materials”. In: Biofilms in Medicine, Industry and

Nandha Engineering College, Erode. He

Environmental Biotechnology - Characteristics, Analysis and

pursued his Master Degree in Engineering

Control, Edited by Lens, P., Moran, A.P., Mahony, T., Stoodly,

Design at Nandha Engineering College, Erode.

P., and O’Flaherty, V., IWA Publishing of Alliance House, 115-

He is currently working as Assistant Professor in Department

131. 2003.

of Mechanical Engineering at Sri Shanmugha College of

[3]International Journal of Environmental Bioremediation &

Engineering and Technology, Sankari. His area of interest

Biodegradation 249 Kumar,R.K.S., Vijian, P., Solomon, J.S. and

includes Alternative Fuels, Finite Element Analysis and

Berchmans, L.J., “Corrosion Studies on Stainless Steel-304 in

Welding.

Brackish Environment.”International Journal of Emerging Technology and Advanced Engineering, 2 (5): 178-182.2012.

A.BALAKRISHNAN completed his Bachelor

[4] Möller, H., Boshoff, E.T.and Froneman,H., “The corrosion

Degree in Mechanical Engineering Sri

behaviour of a lowcarbon steel in natural and synthetic

Shanmugha College of Engineering and

seawaters” The Journal of The South African Institute of

Technology, Sankari. His area of interest

Mining and Metallurgy 106:85-592. 2006.

includes Welding, Automobile and Design.

[5] Wan Nik, W.B, Zulkifli, F., Rahman, M.M., and Rosliza, R., “Corrosion Behavior of Mild Steel in Seawater from Two Different Sites of Kuala Terengganu Coastal Area”, International Journal of Basic & Applied Sciences, 11: 7580.2011.

[6] Wu. J.W., Bai, D., Baker, A.P., Li, Z.-H. and Liu, X.-B., “Electrochemical techniques correlation study of on‐line corrosion monitoring probes”.

BIOGRAPHIES: N.NAVANEETHAKRISHNAN completed his Bachelor Degree in Mechanical Engineering from SSM College of Engineering, Namakkal.

He

pursued

his

Master

Degree

in

Engineering Design at Nandha Engineering College, Erode. He is currently working as Assistant Professor in Department of Mechanical Engineering at Sri Shanmugha College of Engineering and

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